Changer Stop Groove Problem

[Dan Beller-McKenna]

I have been having trouble with the E9 tenth-string on my '82 Super Pro. I lower this string a whole-step on my A pedal, and raise it a whole-step with my LKV. Not too long ago (a month or two), it began returning sharp after a raise. I noticed that it would be corrected by tapping the A pedal or by reaching under the guitar and gently pushing the raise plate of the scissor to the side. At which point it would "click" and the pitch would correct itself. I did a Forum search and found this thread (which I miraculously had the presence of mind to bookmark!!!), which seemed like a possible match to my problem: a groove had worn on the inside edge of the endplate, into which the raise plate was inconsistently landing. See the exchange between Donny Hinson and Wayne Brown near the end of the thread.

viewtopic.php?t=384377

I decided to take a look at things today, anticipating that instead I would find the more familiar finger notch. But with the pull rods removed and the changer finger detached I quickly found the same groove that Wayne had encountered.

Endplate groove.jpg

I suspect the best fix for this is what Wayne did: file the whole edge the depth of the groove (it's only a millimeter or two). I haven't removed the other springs to check each finger, but others might be starting to develop the same problem I suppose this could potentially cause issues with the amount of tension on the return springs or the angle of the fingers at rest. Or maybe it's so slight that it won't really affect anything. Has anyone else encountered this problem and used the same fix as Wayne? Or applied a different solution? I know (from his related post) that Wayne sold this guitar, so he may net be able to speak to the long-term outcome.

Would love to hear from others who have encountered/dealt with this on a Super Pro or on any guitar.

Dan